EP1338398A1 - Apparatus for multicomponent moulding of plastic parts - Google Patents

Abstract

One mold half (7, 8) includes a moveable core (10). One or more injection nozzles with multi-position needle valves (21) are included. The needle adopts not just nozzle opening and closure positions, but is also moved to further positions. In conjunction with the core and the mold halves, this forms distinct cavities (28, 29) for different plastic components (2, 3). The moveable core is in the first mold half (7). One or more nozzles with the multi-position needle, are located in the second mold half (8). In one position the needle is arrested against the core (10) which makes contact with a stop. The first mold half has a cylindrically-symmetrical central section (9); the core is a hollow cylindrical contour slide surrounding and sliding against it and the remainder of the mold half. The core follows the contour of the plastic mold and moves at right angles to it in the first mold half. Further variants based on the foregoing principles are described.

Description

The invention relates to a device for producing multi-component Kunstsotffformteile according to the preambles of the independent claims 1 and Second

In the production of multi-component molded plastic parts using the injection molding process it is known from the prior art, one between the platen Injection molding machine to use rotatable injection molds used in the different Positions form different cavities (see for example DE 41 27 621 C1, WO 98/35808, US 5,246,065).

The disadvantage is that this is basically a turntable with suitable storage and Drive means for rotating the turntable are required. They also have to Injection molds are suitably large in their lateral extent a number of mold nests next to one another corresponding to the number of spraying steps is trainable.

To remedy this disadvantage, a device for the manufacture of vessel lids is known from the generic DE 195 08 509 A1, in which differently shaped cavities can be formed between two mold halves without using a rotary table, as will be explained in more detail below:
The device according to the prior art has a first, lower mold half, a second, upper mold half, and in the lower mold half a cylindrical tool center part and a hollow cylindrical core surrounding it. The core can be moved back and forth by means of a drive device. The thermoplastic component for the vessel lid is injected via hot runner nozzles in the parting plane of the mold halves. One or more needle valve nozzles for injecting the elastomer component for the cover seal are arranged in the upper mold half in the region of the cover edge. These needle valve nozzles each have a nozzle needle which, in addition to the open position in which the melt outlet opening is released and a closed position in which the melt outlet opening is closed, can be moved out of the nozzle housing and the melt outlet opening.
The operation of this known device is as follows:
In a first injection step for the thermoplastic component, the core is in its forward position and the nozzle needle of the needle valve nozzle of the elastomer component is moved out of its housing, to the stop with the end face of the core. The needle valve nozzle for the elastomer component is closed and penetrates the cavity of the thermoplastic component. A hole is formed in the vessel lid in this area. When the vessel lid has cooled sufficiently, the core is moved backwards by a short distance, so that a second, annular cavity for the sealing ring made of the elastomer component is formed between the underside of the vessel lid and the end face of the core. The nozzle needle is moved back to the rearmost position, so that the melt outlet opening for the elastomer component is released and the elastomer melt can flow into the second cavity via the hole in the bucket lid. After the second cavity has been filled, the nozzle needle is moved forward so far that the end face of the nozzle needle is flush with the upper mold half and the vessel lid is given a flat surface in this area. The sealing ring is thus formed on the underside of the bucket lid and penetrates it in the area of the hole in the vessel lid, that is to say in the area in which the nozzle needle was in contact with the core in the first injection step. If a plurality of needle valve nozzles are used for injecting the elastomer component, the number of these valve valve nozzles will result in a large number of holes being formed in the vessel cover, into which the sealing ring protrudes.

In this way, multi-component plastic parts can be made without a turning tool getting produced. However, it is disadvantageous that the second component is connected by a channel the first component is injected so that it is on the surface of the first Component places where the second component is visible. The first Component quasi "defects".

It may now be necessary, especially in the case of high-quality, multi-component Plastic parts that the first component free from such production-related "Flaws" is and the surface instead consistently from only one component consists.

The invention is therefore based on the object, starting from the generic State of the art to provide a device with the multi-component Plastic molded parts without breakthroughs or "missing parts" and without using a Turning tool can be produced.

This object is achieved by a device with the features of independent claims 1 and 2. Advantageous further developments and Refinements can be found in the subclaims. The essence of the present invention is it, in one of the mold halves a sliding core and in this one or more To provide valve gate nozzles, the nozzle needles next to the open and Closed position can be moved into other positions and with the core and other parts of the mold halves interact in such a way that for different Plastic components different cavities can be formed. A first advantage The present invention is therefore that in this way entirely on one Turning tool can be dispensed with. A second advantage arises from the fact that the Needle valve nozzles are housed in the core, which is why the components are such can be injected so that they do not penetrate each other and therefore no "missing parts" be formed. Depending on the molded part, the needle valve nozzle itself can also be used Front end help with the remaining parts of the mold halves and the core Form cavities (claim 2). Depending on the molded part and mold design, you can also needle shut-off nozzles that can be moved in relation to the core and fastened in the core combine with each other (dependent claim 4), which is the versatility of the present Invention clarifies.

Fig.1:

Eimer und Deckel mit angespritztem Dichtring gemäß der Erfindung;

Fig. 2a - 2b:

erste Ausführungsform eines erfindungsgemäßen Spritzgießwerkzeugs in verschiedenen Arbeitsstellungen;

Fig. 3a - 3b:

zweite Ausführungsform eines erfindungsgemäßen Spritzgießwerkzeugs in verschiedenen Arbeitsstellungen.

The invention is to be explained in more detail below on the basis of exemplary embodiments and with reference to FIGS. 1 to 3b.
Show it:

Fig.1:

Bucket and lid with molded sealing ring according to the invention;

2a-2b:

first embodiment of an injection mold according to the invention in different working positions;

3a - 3b:

second embodiment of an injection mold according to the invention in different working positions.

The invention is based on a device for producing a thermoplastic Bucket lid can be described with an elastomer seal. It goes without saying that the invention is not based on the production of thermoplastic parts with molded Elastomer part is limited, but is also suitable for other plastic composites, i.e. is universally usable in multi-component and multi-color injection molding.

With the invention, a bucket lid 2 with a sealing ring 3 can be produced, as shown in FIG. 1 is shown. FIG. 1 shows a bucket 1 made of an injection molded in a conventional manner thermoplastic and the placed thereon with an inventive Device produced bucket lid 2 with a sealing ring 3 made of an elastomer. The Bucket lid 2 has on its outer edge a section 4 with a substantially U-shaped Cross section and a bead 5 at the lower end of this section. To this The bucket lid 2 sits tightly and firmly on the bucket 1. Suitable combinations for the plastic composite are, for example, PP for the bucket lid 2 and EPDM for the Sealing ring 3 or PA for the bucket lid 2 and LSR for the sealing ring 3. The surface of the Bucket lid 2 is continuous and has no interruptions.

Figures 2a and 2b show a first embodiment of an inventive Injection mold for producing such a bucket lid.

An injection mold 6 has a first, lower mold half 7, a second, upper Mold half 8, and a core 10 in the upper mold half 8. The core 10 is corresponding to the molded part to be produced, essentially cylindrical symmetrical and Contour of the sealing ring to be produced following a hollow cylindrical shape. About one here The drive device (not shown) can advance the core 10 relative to the mold half 8 can be reduced. Furthermore, a stripper 12 is in the lower mold half 7 provided that via several rods 13 to a drive device, not shown here is connected, with which the scraper 12 can be moved back and forth, wherein when driving up a finished bucket lid 2 with sealing ring 3 from the lower mold half 7 stripped and by means of a removal handling from the open injection mold can be removed.

In the upper mold half 8 is for injecting the thermoplastic component for the bucket lid 2 in the center of the mold half a first needle valve 14, in essentially consisting of the nozzle housing 15, a melt channel 16 and one Nozzle needle 17 in the needle valve nozzle between an open position in which the Melt outlet opening 18 is released and a closed position in which the Melt outlet opening 18 is closed, is movable. The nozzle housing 15 is only at a few points 19 in contact with the mold half 8 and otherwise forms an annular gap 20, so that it is thermally insulated from the mold half 8.

Furthermore, there are one or several further needle valve nozzles 21 for injecting the elastomer component arranged. When it comes to the manufacture of bucket lids with molded sealing rings, it has become a reality proven to use two to four such valve gate nozzles distributed over the circumference. For the sake of clarity, only one of these needle valve nozzles is shown in the figures located. These valve gate nozzles essentially have a nozzle housing 22, a melt channel 23 and a nozzle needle 24. The latter is next to the Open position in which the melt outlet opening 25 is released and one Closed position, in which the melt outlet opening 25 is closed, in further Positions out of the nozzle housing 22 and the melt outlet opening 25 movable, whereupon further in the description of the operation of the device is received. The nozzle housing 22 is only in contact with the at a few points 26 Mold half 8 and forms an annular gap 27, so that it is opposite the mold half 8 is thermally insulated.

The projecting, annular front end piece 34 of the core 10 has a bore 38 with a diameter corresponding to the diameter of the nozzle needle 24 and can move to the stop with the annular front part 35 of the lower mold half 7 be an annular recess 36 for the formation of the sealing ring 3rd having.

In a first injection step (FIG. 2a), the elastomer component, So the sealing ring 3 injected. For this purpose, the core 10 is at the stop with the front part 35 of the lower mold half 7, so that the recess 36 is covered and a cavity 29 is formed for the elastomer component. The nozzle needle 24 of the The elastomer component is in the rear (open) position and the Elastomer melt can flow into the cavity 29. During this time it is Needle valve nozzle 14 closed for the thermoplastic component. If the sealing ring 3 is hardened sufficiently, the nozzle needle 24 is advanced so far that the end face the nozzle needle 24 is flush with the end face of the end piece 34 of the core 10. Subsequently or in parallel, the core 10 is moved a short distance to the rear process so that the end face of the end piece 34 is flush with the surface of the mold half 8 completes in this area. In this way, the cavity 28 for the Thermoplastic component, that is, the bucket lid 2, formed and the needle valve nozzle 14th the thermoplastic component can be opened (second injection step, see Fig.2b).

When the bucket lid 2 has cooled sufficiently, it can be removed by means of the wipers 12 lower mold half 7 and removed from the injection mold.

Figures 3a and 3b show a second embodiment of the invention, the Modification to the first embodiment described above is that the Core 10 is continuously designed as a component with a cylindrical cross section and that the Needle valve nozzle 14 for the thermoplastic component in a central bore in the core 10 is movable. The front end piece 37 of the nozzle housing 15 is designed such that its end face is flat and can be positioned flush with the end face of the core 10. In the first injection step, as in the previously described exemplary embodiment, the Cavity 29 formed for the elastomer component and the sealing ring 3 formed. If the Sealing ring 3 is sufficiently hardened, the nozzle needle 24 is advanced so far that the The end face of the nozzle needle 24 is flush with the end face of the end piece 34 of the core 10 concludes. Subsequently or in parallel, the core 10 is moved a short distance Move back so that the front of the front end piece 34 of the core 10 is flush with the surface of the mold half 8 closes in this area. In parallel, the Move the needle valve nozzle 14 forward so far that the front of the front End piece 37 of the nozzle housing 15 flush with the end face of the core 10 in this Area closes. Alternatively, the needle valve nozzle 14 can also be in the beginning are in this position, so that only the core 10 is moved back into this position must become. In this way, the cavity 28 for the thermoplastic component, ie the Bucket lid 2, formed and the needle valve nozzle 14 for the thermoplastic component can be opened. When the bucket lid 2 has cooled sufficiently, it can be removed using the Scraper 12 lifted off the lower mold half and out of the injection mold be removed.

LIST OF REFERENCE NUMBERS

1

bucket

2

bucket lid

3

Elastomeric sealing ring

4

U-shaped edge of the bucket lid

5

bead

6

injection mold

7

Lower mold half

8th

Upper mold half

9

-

10

core

11

-

12

scraper

13

Operating rods for the wiper

14

Needle valve for the thermoplastic component

15

Nozzle housing of the needle valve nozzle 14

16

Melt channel for the thermoplastic component

17

Nozzle needle of the needle valve nozzle 14

18

Melt outlet opening for the thermoplastic component

19

Contact points of the needle valve nozzle 14

20

Annular gap between the needle valve nozzle 14 and the mold half 8

21

Needle valve for the elastomer component

22

Nozzle housing of the needle valve nozzle 21

23

Melt channel for the elastomer component

24

Nozzle needle of the needle valve nozzle 21

25

Melt outlet opening for the elastomer component

26

Contact points of the needle valve nozzle 21

27

Annular gap between the needle valve nozzle 21 and the mold half 8

28

Cavity for the thermoplastic component

29

Cavity for the elastomer component

30

-

31

-

32

-

33

-

34

Front end of the core 10

35

Front part of the lower mold half 7

36

Annular recess

37

Front end part of the nozzle housing 15

38

Bore in the core 10 for the nozzle needle 24

Claims (9)

Device for injection molding multi-component plastic molded parts, with a first mold half (7) and a second mold half (8), one of the mold halves (7, 8) having a displaceable core (10), at least one needle valve nozzle (21) having a multi-adjustable one Nozzle needle (24) is provided, and these nozzle needles (24) can be moved into several positions such that the nozzle needles (24) can be moved into further positions in addition to the open and closed positions, in such a way that the nozzle needles (24) are in the different positions further positions together with the core (10) and the two mold halves (7, 8) form different cavities (28, 29) for different plastic components (2, 3),
characterized in that the core (10) and one or more of the needle shut-off nozzles (21) equipped with the multi-adjustable nozzle needles (24) are arranged in the same mold half (8), that these needle shut-off nozzles (21) are fastened in the core (10) and that the core (10) has a bore (38) through which the nozzle needles (24) of these needle valve nozzles (21) can be moved. Device for injection molding multi-component plastic molded parts, with a first mold half (7) and a second mold half (8), one of the mold halves (7, 8) having a displaceable core (10), and one or more needle valve nozzles (14, 21) are provided
characterized in that the needle valve nozzles (14, 21) are arranged in the core (10), that the needle valve nozzles (14, 21) and the core (10) can be moved relative to one another and that the front ends (37) of these valve valve nozzles (14 , 21) with the core (10) and the mold halves (7, 8) can form cavities (28, 29). Device according to claim 2,
characterized in that at least one of the movable needle shut-off nozzles (21) is equipped with a multi-adjustable nozzle needle (24), the nozzle needle (24) being movable into several positions such that the nozzle needle (24) in addition to the open and closed position in further Positions can be moved such that the nozzle needle (24) forms cavities in the various other positions together with the front end of the needle valve nozzle (21), the core (10) and the two mold halves (7, 8). Device according to claim 2 or 3,
characterized in that, in addition to the movable valve gate nozzles (14), one or more further valve gate nozzles (21) are fastened in the core (10), and in that the core (10) has bores (38) through which the nozzle needles (24) pass Needle valve nozzles (21) can be moved through. Use of a device according to one of claims 1 to 8 for manufacture of a multi-component molded plastic part (1), comprising a thermoplastic part (2) and an elastomer part (3), the elastomer part (3) via the needle valve nozzles (21) is injected with the multi-adjustable nozzle needles (24). Use according to claim 9,
characterized in that PP is used for the thermoplastic part (2) and EPDM for the elastomer part (3). Use according to claim 9,
characterized in that PA is used for the thermoplastic part (2) and LSR for the elastomer part (3). Use according to one of claims 9 to 11,
characterized in that an adhesion promoter is added to one or more plastic components. Use according to one of claims 9 to 11 for the production of a thermoplastic cover (2) with a molded elastomer seal (3).

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